Published online Dec 15, 2026. doi: 10.4251/wjgo.124885
Revised: August 4, 2026
Accepted: September 15, 2026
Published online: December 15, 2026
Processing time: 122 Days and 3.9 Hours
Postoperative nutritional problems are the most prevalent complication following gastric surgery for gastric cancer, which seriously impacts patient health and longevity. Several studies have demonstrated that the gut microbiota and their metabolites are essential in regulating host nutrient metabolism; nonetheless, the dynamics and the relationships between gut microbiota, serum metabolites, and nutrient malabsorption following gastrectomy are still poorly understood.
To investigate dynamic changes in gut microbiota and serum metabolites after gastrectomy and their association with malnutrition.
This prospective observational cohort study enrolled three groups: Distal gastrectomy group (n = 38), total gastrectomy group (n = 34), and endoscopic submucosal dissection (ESD) group (n = 33). Fecal and fasting venous blood samples were collected at preoperative baseline (T0), 1-2 weeks postoperatively (T1), 3-6 months postoperatively (T2), and 12 months postoperatively (T3). High-throughput sequencing of the V3-V4 hypervariable region of the 16S rRNA gene was performed using the Illumina NovaSeq 6000 platform, and serum bile acid and amino acid concentrations were detected using ultra-high-performance liquid chromatography-tandem mass spectrometry.
Following gastrectomy, gut microbiota α-diversity significantly declined, and β-diversity markedly changed (P < 0.05). In distal and total gastrectomy groups, pathogenic bacteria (Streptococcus, Veillonella) increased by 460%-634%, while beneficial bacteria [Faecalibacterium prausnitzii (F. prausnitzii), Bifidobacterium] decreased by 85%-98%; populations remains stable in the ESD group (< 6% change). Serum total bile acids increased by ~100% in gastrectomy groups but decreased 11.1% in the ESD group; branched-chain amino acids consistently drop ~11%-13% across all groups. In severe malnutrition vs well-nourished patients at 12 months, Bifidobacterium was 40.9% lower, F. prausnitzii was 24.1% lower, and Streptococcus was 16.3% higher. Spearman correlation showed that F. prausnitzii and Bifidobacterium positively correlated with body mass index, weight, and albumin (ρ = 0.21-0.25) and negatively correlated with bile acids (ρ = -0.32 to -0.64); Streptococcus and Veillonella showed opposite correlations.
Post-gastrectomy malnutrition is linked to gut dysbiosis and bile acid disturbances, with severity related to surgical extent. ESD, which preserves gastric anatomy, maintains microbial homeostasis. Early microbiota shifts may predict long-term nutritional outcomes.
Core Tip: This prospective longitudinal study compared the dynamic effects of distal gastrectomy, total gastrectomy, and endoscopic submucosal dissection on gut microbiota and serum metabolites in gastric cancer patients. A surgery-extent-dependent gradient of dysbiosis and bile acid metabolic disturbances was observed. Endoscopic submucosal dissection preserved gastric integrity, thereby maintaining microbial homeostasis. Early postoperative Streptococcus overgrowth may serve as an early warning sign of long-term malnutrition.